Date of Award

1-1-2011

Document Type

Campus Access Dissertation

Department

Civil and Environmental Engineering

First Advisor

Juan M Caicedo

Abstract

This work presents the development of scalable reduced models for the through-the soil interaction and traveling wave effects of distant sleepers in a long railway track. For development purposes, and, without loss of generality, the geometry of the sleepers is consistent with the UIC-60 track system commonly used in European High Speed Rail. The proposed reduced models are based on B Spline Impulse Response Functions (BIRF) of the sleepers only as computed through Boundary Element Method (BEM) solutions of the full model, preserve the frequency content of the full models, and they are highly accurate within the assumptions of linear isotropic and homogeneous soil media. They are expressed in a scalable form with respect to soil properties and sleeper spacing. In particular, the BIRFs of distant sleepers can be accurately approximated by appropriate scaling operations of time and amplitude of a reference sleeper BIRF while retaining all dynamic characteristics of the full model. Three main scaling parameters are introduced: (i) the apparent propagation velocity, (ii) the geometric damping coefficient, (iii) soil properties of a reference soil (i.e., the shear modulus and shear wave velocity). The models are validated through comparisons with other BEM solutions, and the accuracy and efficiency are established. The proposed models are developed as part of an NSF funded research on vibrations induced by High Speed Rail traffic and are consistent with the associated train and rail models and a Multi System Interface Coupling (MSIC) technique that were developed as part of the project and presented in companion research documents. The proposed approach forms the framework for developing scaled reduced models for other vibration modes and different sleeper geometries and can be generalized to include any foundation type or layered soil profiles.

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